100 MR. W. H. FLOWER ON THE OSTEOLOGY OF 
rib, is effected, not in this case by the disappearance of either the lower or the upper 
attachment, but by their gradual coalescence. 
In Platanista the attachment of the ribs is again different in detail, being something 
between that found in the true Delphinide and in Inia. Fach of the first seven ribs 
is attached to the transverse process of its own vertebra and to the body chiefly of 
the preceding vertebra; but the transverse processes differ from those of the Del- 
phinide in being very short, and in being more rapidly transferred down to the 
bodies; indeed this takes place as early as the sixth vertebra, and before the disap- 
pearance of the articular facet for the head of the rib, leading to a blending of the two 
articulations in one as in Jnia. 
The remaining vertebre (lumbo-caudal) are twenty-one in number. In accordance 
with the usual (and most correct custom) of reckoning the caudal region of the Cetacea 
as commencing with the first vertebra which bears a chevron bone*, there are but three, 
or at most four, vertebrae, which can properly be called lumbar. The uncertainty rests 
upon the difficulty of determining, in a skeleton of which the bones are all separated, 
and in which, owing to its immaturity, the articular surfaces and processes are not very 
distinctly marked, to which of the vertebra the first (always very small) pair of hema- 
pophyses was attached. I think, however, that there can be little doubt that the 
fourth of the vertebree behind the thoracic region did bear such bones, not only from 
indications on its own surface, but also because the facets on the hinder edge of the 
under surface of the fifth are too strongly pronounced to be the attachments of the 
small first pair. Taking, then, the true lumbar vertebre at only three, Jia presents 
* As a uniform system of nomenclature in enumerating the vertebre of Cetacea is very desirable, it is to be 
regretted that Eschricht and Reinhardt, in their most recent works on Cetology, should have given the weight 
of their high authority to reckoning as the last of the lumbar vertebre the one immediately preceding the first 
chevron bone, and which has commonly been regarded as the first caudal. The only reason given for this 
change is, that “the anus, which may justly be said to mark externally the limits between the abdomen and the 
tail, is situated directly beneath the first chevron bone” !, This, however, does not prove the case ; for if we 
look at the skeleton of any terrestrial mammal in which the distinction between the different regions of the 
vertebral column is definitely marked, we may see that the commencement of the caudal region is situated some 
way in front of the position of the anus. We ought rather, according to this criterion, to reckon two or three 
of the vertebrae in the Cetacea commonly called lumbar to the region of the tail,—a view further strengthened 
by the fact that, in the ordinary mammals, the chevron bones, when present, begin generally not on the first, but 
on the second or third caudal vertebra. Such a division would, however, be quite impracticable. 
Bach cheyron bone belongs essentially to the vertebra in front of it. This is most clearly seen when they are 
small, as in the commencement of the series. In the skeleton of a Physeter that I lately examined, the first is 
even ankylosed to the posterior edge of the body of its proper vertebra, and has no connexion with that behind 
it. Itis quite certain that any vertebra bearing a chevron bone cannot consistently be regarded as one of the 
lumbar series. We may therefore conyeniently reckon the first vertebra which is so distinguished as the com- 
mencement of the caudal region. 
1 Recent Memoirs on the Cetacea, published by the Ray Society, 1866: Eschricht and Reinhardt on the 
Greenland Whale; p. 105; and Reinhardt on Pseudorca crassidens, p. 204. 
